also: じかんのムダ
A common phrase meaning that an activity or effort is not worth the time spent.
Doing that is a waste of time.
The meeting was too long and a waste of time.
無駄 is a general adjective/noun meaning 'useless' or 'wasteful'; 時間の無駄 specifically refers to wasted time.
時間の浪費 is a more formal or written expression for 'waste of time', while 時間の無駄 is common in everyday speech.
Standard kanji spelling.
Mixed kanji-kana spelling; common in casual writing.
Katakana spelling of むだ; adds emphasis or a casual tone.
Compound of 時間 (time) + の (possessive particle) + 無駄 (waste, futility).